An Australian scientist says he is "completely blown away" after being given the job of searching for alien life forms in a new $135 million push financed by Stephen Hawking and Russian billionaire Yuri Milner.

Australia will play a crucial role in the Breakthrough Listen project's hunt for extraterrestrial life, with the Parkes Observatory in New South Wales signing a multi-million-dollar contract to scan radio waves for life in the cosmos.

The CSIRO has signed a deal for the Breakthrough Prize Foundation to use the Parkes telescope to look for intelligent life on the closest stars to Earth, beyond the Milky Way and into other galaxies.

It has been described as the "biggest scientific research" project looking for signs of intelligent life, and will cover 10 times as much of the sky than previous programs.

Professor Matthew Bailes from Melbourne's Swinburne University was let in on the secret mission just a few days ago and he is still coming to terms with the announcement.

He will be the project's lead investigator at the Parkes Telescope.

"I was completely blown away, in fact I have to still pinch myself that I'm not dreaming, it's an amazing cash investment in the science we do, and it's astounding really," he said.

At the launch of the project in London, physicist Professor Hawking said it was time to find out if extraterrestrial life existed.

"We believe that life arose spontaneously on Earth, so in an infinite universe, there must be other occurrences of life," he said.

"Somewhere in the cosmos, perhaps, intelligence may be watching these lights of ours, aware of what they mean.

We know there's lots of worlds out there, but whether or not there's little green men on there is something we still don't know.

Professor Matthew Bailes

"Or do our lights wander a lifeless cosmos?"

The CSIRO will contract a quarter of the telescope's time for five years to scan for potential radio signals from galaxies beyond our reach.

"Radio waves are a very efficient way of transmitting information and it's likely that aliens, if they're into interstellar communication at all, would be using the radio part of the spectrum," Professor Bailes said.

"We know there's lots of worlds out there, but whether or not there's little green men on there is something we still don't know."

Professor Bailes said the Parkes telescope was well placed to be part of the research.

"It's one of the largest radio telescopes on Earth," he said.

"It's not so close to a city that it's destroyed by human transmissions but it is increasingly threatened by things like mobile phones and the demands for the spectrum by you and I, I guess."

Parkes telescope seeking signals not coming from natural sources

Professor Fred Watson from the Australian Astronomical Observatory in Canberra said the Parkes telescope would be trying to pick up signals that were not coming from natural sources.

"[The task will be] to look for specific signals that might have an intelligent origin," he said.

"Never before have we directed projects like the one we're talking about now."

Professor Watson said the survey would be scanning for either signs of life or extraterrestrial beings.

"What you're doing is you're trying to use the telescope in such a way that it will search for signals that have got no known naturally occurring counterpart."

Amateur astronomer Alex Abbey from the Central West Astronomical Society said if signs of life were found, it did not necessarily mean extraterrestrial life still exists.

"Even if they did find some evidence of intelligent life out there somewhere, it doesn't mean that we're about to be buzzed by UFOs because the distances are so great," he said.

"Even radio waves travelling at the speed of light, if we found any evidence, that radio signal could well have left its originating planet at billions or at least millions of years ago and that civilisation may not exist anymore."

The discovery of alien life has been fodder for Hollywood for decades, but astronomers who search for extraterrestrial intelligence have had trouble securing funding for their quest.

Russian entrepreneur Milner, who has carved out a career investing in Silicon Valley, is the sole investor.

"It is time to open our eyes, our ears and our minds to the cosmos," he said.

Cosmologist Professor Paul Davies from Arizona State University has spent his career studying the question of what else is out there.

"This is the big unknown in this entire quest," he said.

"We've got no idea how many planets might have life on them, it might be a very, very small number but if you don't look, you don't find out.

"So it's fantastic that at last, not only do we have senior scientific figures on side, but we have a seriously large budget to be able to do this in a systematic manner."

He said there are no easy answers as to what happens next if intelligent life is found.

"Should we respond? Who gets to speak for us? What do we do next?" he said.

"There are no easy answers to these but if we're going to engage in a dialogue with an alien civilisation this is something that needs the consideration of everybody on the planet."